As a vacuum pump utilized for industry, there are a pumping-out type pump and an entrapment type pump. The pumping-out type pump is a pump in which gas is sucked from an intake port, compressed inside of the pump, and drawn out from an exhaust port. A mechanical pump in which gas is compressed by rotating blades or gears using a motor is one of pumping-out type pumps, and as for this kind of pumps, such as an oil rotary pump, a diaphragm pump, a roots pump, and a turbo molecular pump are of practical use. In addition, a steam jet type pump which kicks out gaseous molecules using a high-speed oil vapor jet is also one of the pumping-out type pumps. On the other hand, the entrapment type pump is a pump which decompresses an outside of the pump by capturing gas into an inside thereof from the outside and performs recovery operation in which the captured gas is discharged to the atmosphere after the pumping operation is finished. For this kind of pumps, such as a cryopump, a sorption pump and a getter pump are utilized.
In recent years, a new type vacuum pump called as a Knudsen compressor has been studied as one of the pumping-out type pumps (refer to the patent documents 1, 2 and non-patent document 1, for example). This pump (a compressor is considered to be one concept of a pump in this specification) utilizes thermal transpiration flow in which gas flows from low-temperature side to high-temperature side in a pipe which has a temperature gradient along its axis. The Knudsen compressor is significantly different from prior mechanical pumps in the point that the gas can be transported without using moving parts.
In addition, as a behavior of gas to be generated owing to a temperature field of the gas, existence of thermal edge flow by which gas flow is induced in a periphery of a sharp edge of an object when the object is put in a gas atmosphere being heated or cooled has been pointed out (non-patent document 2), and it has been experimentally confirmed (non-patent document 3). However, a pump apparatus utilizing the thermal edge flow has not been considered at all.
Patent document 1: U.S. Pat. No. 5,871,336
Patent document 2: JP-A-2001-223263
Non-patent document 1: Y. Sone and H. Sugimoto, Vacuum pump without a moving part and its performance, in Rarefied Gas Dynamics, ed. by A. D. Ketsdever and E. P. Muntz (AIP, New York, 2003) 1041-1048
Non-patent document 2: K. Aoki, Y. Sone, and N. Masukawa, “A rarefied gas flow induced by a temperature field,” in Rarefied Gas Dynamics, ed. by G. Lord (Oxford U.P., Oxford, 1995) 35-41
Non-patent document 3: Y. Sone and M. Yoshimoto, “Demonstration of a rarefied gas flow induced near the edge of a uniformly heated plate,” Phys. Fluids 9 (1997) 3530-3534